This week's winner to the is jahigginbotham. Good job. The answer is a mechanical equivalent of heat apparatus. Here are a couple of pictures from the manual (which I was surprised to find):
What is mechanical equivalent of heat? Basically, it is connecting the idea of Work-Energy:
with the idea of thermal energy and temperature:
The way these kinds of labs work (get it?) is that you take some known force that does work in a situation that changes the thermal energy of an object. You measure the change in temperature and compare to the work. The last time I tried one of these as a lab, it didn't go as well as expected.
So, how does this apparatus work? The basic idea is that there are two metal cones that rub against each other. The bottom cone rotates while the top one is stationary. The pulley in the diagram holds the top cone stationary. If you know this force, the distance to the point of rotation and the number of rotations you can calculate the work done in rotating the bottom cone (the torque is the same). Once you know the work, you can compare it to the change in thermal energy for the two cones (the top cone has some water so that you can measure the temperature easily).
I wanted to make a video of this sucker functioning, but I failed. My driving motor was messed up. However, this would make a pretty interesting lab. The thing I like is that students could take it to different levels. Maybe you just want to calculate the work and compare to the change in thermal energy. Or maybe you want to go a little bit further.
At the next level, a student could try to take into account the energy lost due to radiation and conduction effects.
